Egypt has extensive environmental pollution and the highest proportion of early-onset colorectal cancers in patients under age 40 in the world (35 percent of total colorectal cancers). These tumors show high mucin production, more undifferentiation, and a lower prevalence of k-ras mutations that tumors of US patients. The molecular and pathological patterns of these tumors could indicate possible environmental exposures. Organochlorine pesticides, polycyclic aromatic hydrocarbons (PAHs), heterocyclic amines (HCAS), and polychlorinated biphenyls (PCBs) have been correlated with colon carcinogenesis in experimental animals. Egyptians are highly exposed to these carcinogens in farming, cooked foods, combustion products, and polluted air and water. Egypt offers a unique opportunity and a natural experiment for a population study to investigate the impact of organochlorine pesticides and other environmental carcinogens on early-onset colorectal cancer. In order to better understand the association between pesticide exposure, other environmental carcinogens and early-onset colorectal cancer, we propose a case-control study to determine the relationship between exposure to these carcinogens, and colorectal cancer risk in 150 colorectal cancer patients and 150 non-cancer controls under age 40 in Egypt. History of environmental, occupational, and residential exposures to these compounds will be collected from cases and compared with that of controls. We will also compare clinical characteristics such as tumor site and pathological characteristics such as mucin production in cases with epidemiologic profiles and environmental exposures. In addition, we will also collect biological specimens from cases and controls for future studies. These epidemiologic data will help us better characterize the most suspect environmental exposures for a more focused investigation of gene-environment interactions. Results from this study will provide clues to colorectal cancer etiology and lead to a large-scale study.